[Mesa-dev] [PATCH] llvmpipe: Honour pipe_rasterizer::point_quad_rasterization.

[Jose Fonseca]

----- Original Message -----
> Am 08.01.2014 18:27, schrieb jfonseca at vmware.com:
> > From: José Fonseca <jfonseca at vmware.com>
> > 
> > Commit eda21d2a3010d9fc5a68b55a843c5e44b2abf8dd fixed the rasterization
> > of points for Direct3D but ended up breaking the rasterization of OpenGL
> > non-sprite points, in particular conform's pntrast.c test.
> > 
> > The only way to get both working is to properly honour
> > pipe_rasterizer::point_quad_rasterization, and follow the weird OpenGL
> > rule when it is false.
> > ---
> >  src/gallium/drivers/llvmpipe/lp_setup_point.c | 64
> >  ++++++++++++++++++++++-----
> >  1 file changed, 54 insertions(+), 10 deletions(-)
> > 
> > diff --git a/src/gallium/drivers/llvmpipe/lp_setup_point.c
> > b/src/gallium/drivers/llvmpipe/lp_setup_point.c
> > index 988e0c5..e5ce4ee 100644
> > --- a/src/gallium/drivers/llvmpipe/lp_setup_point.c
> > +++ b/src/gallium/drivers/llvmpipe/lp_setup_point.c
> > @@ -338,9 +338,13 @@ try_setup_point( struct lp_setup_context *setup,
> >     int fixed_width = MAX2(FIXED_ONE,
> >                            (subpixel_snap(size) + FIXED_ONE/2 - 1) &
> >                            ~(FIXED_ONE-1));
> >  
> > -   const int x0 = subpixel_snap(v0[0][0] - setup->pixel_offset) -
> > fixed_width/2;
> > -   const int y0 = subpixel_snap(v0[0][1] - setup->pixel_offset) -
> > fixed_width/2;
> > -
> > +   /* Yes this is necessary to accurately calculate bounding boxes
> > +    * with the two fill-conventions we support.  GL (normally) ends
> > +    * up needing a bottom-left fill convention, which requires
> > +    * slightly different rounding.
> > +    */
> > +   int adj = (setup->bottom_edge_rule != 0) ? 1 : 0;
> > +
> >     struct lp_scene *scene = setup->scene;
> >     struct lp_rast_triangle *point;
> >     unsigned bytes;
> > @@ -363,13 +367,14 @@ try_setup_point( struct lp_setup_context *setup,
> >        print_point(setup, v0);
> >  
> >     /* Bounding rectangle (in pixels) */
> > -   {
> > -      /* Yes this is necessary to accurately calculate bounding boxes
> > -       * with the two fill-conventions we support.  GL (normally) ends
> > -       * up needing a bottom-left fill convention, which requires
> > -       * slightly different rounding.
> > +   if (!lp_context->rasterizer ||
> > +       lp_context->rasterizer->point_quad_rasterization) {
> > +      /*
> > +       * Rasterize points as quads.
> >         */
> > -      int adj = (setup->bottom_edge_rule != 0) ? 1 : 0;
> > +
> > +      const int x0 = subpixel_snap(v0[0][0] - setup->pixel_offset) -
> > fixed_width/2;
> > +      const int y0 = subpixel_snap(v0[0][1] - setup->pixel_offset) -
> > fixed_width/2;
> >  
> >        bbox.x0 = (x0 + (FIXED_ONE-1)) >> FIXED_ORDER;
> >        bbox.x1 = (x0 + fixed_width + (FIXED_ONE-1)) >> FIXED_ORDER;
> > @@ -380,8 +385,47 @@ try_setup_point( struct lp_setup_context *setup,
> >         */
> >        bbox.x1--;
> >        bbox.y1--;
> > +   } else {
> > +      /*
> > +       * OpenGL rasterization rules for non-sprite points.
> Maybe add "legacy" here before OpenGL?

Sure.

> > +       *
> > +       * Per OpenGL 2.1 spec, section 3.3.1, "Basic Point Rasterization".
> > +       */
> > +
> > +      const int x0 = subpixel_snap(v0[0][0]);
> > +      const int y0 = subpixel_snap(v0[0][1]) - adj;
> > +
> > +      int int_width = fixed_width >> FIXED_ORDER;
> > +
> > +      assert(setup->pixel_offset != 0);
> > +
> > +      if (int_width == 1) {
> > +         bbox.x0 = x0 >> FIXED_ORDER;
> > +         bbox.y0 = y0 >> FIXED_ORDER;
> > +         bbox.x1 = bbox.x0;
> > +         bbox.y1 = bbox.y0;
> > +      } else {
> > +         if (int_width & 1) {
> > +            /* Odd width */
> > +            bbox.x0 = (x0 >> FIXED_ORDER) - (int_width - 1)/2;
> > +            bbox.y0 = (y0 >> FIXED_ORDER) - (int_width - 1)/2;
> > +         } else {
> > +            /* Even width */
> > +            bbox.x0 = ((x0 + FIXED_ONE/2) >> FIXED_ORDER) - int_width/2;
> > +            bbox.y0 = ((y0 + FIXED_ONE/2) >> FIXED_ORDER) - int_width/2;
> > +         }
> > +
> > +         bbox.x1 = bbox.x0 + int_width - 1;
> > +         bbox.y1 = bbox.y0 + int_width - 1;
> > +      }
> >     }
> > -
> > +
> > +   if (0) {
> > +      debug_printf("  bbox: (%i, %i) - (%i, %i)\n",
> > +                   bbox.x0, bbox.y0,
> > +                   bbox.x1, bbox.y1);
> > +   }
> > +
> >     if (!u_rect_test_intersection(&setup->draw_regions[viewport_index],
> >     &bbox)) {
> >        if (0) debug_printf("offscreen\n");
> >        LP_COUNT(nr_culled_tris);
> > 
> 
> This looks good to me. Note though this type of point rasterization is
> only available in pre 3.0 contexts (or compatibilility contexts which we
> don't support) anyway.

Oh really!?  Argh..  It though it was still relevant nowadays, or I wouldn't have wasted my afternoon on trying to figure out the regression and the proper fix...

Well, what's done is done.  Thanks for reviewing.

Jose